All purchased chocolate has gone through a process called tempering, a controlled raising and lowering of temperature to stabilize chocolate’s characteristics and to give it a fine gleam, uniform color and a sharp snap when broken. Once chocolate has been melted at 116-118 degrees Fahrenheit, it loses its temper. Loss of tempering will not make a difference if the chocolate will be combined with another ingredient(s). Chocolates destined for use in dipping, molding, or coating on the other hand, will require re-tempering.
Chop about 3/4 of the chocolate to be tempered into small pieces and place in the top of double boiler. Water in the double boiler should not be hot (not simmering or boiling). This is important because if steam or stray water droplets come into contact with the chocolate, the droplets may cause the chocolate to tighten into a stiff unworkable mass. Stir frequently with a rubber spatula to ensure even melting, until all of the chocolate has re-melted. Remove from heat. Add the remaining chunk to the melted chocolate (it acts like an ice cube). Continue to stir until the temperature of the melted chocolate tests cool to the touch (about 88 degrees). A good way to test the temperature is to dab a drop of chocolate to your bottom lip. It should feel slightly cooler than your body temperature. Not all of the chocolate chunk will necessarily melt and whatever is left should be removed when the proper temperature (~88 degrees) is reached.
When you are through dipping, place in the refrigerator so the chocolate will set. Before storing, allow your freshly dipped chocolates to cool for one hour. Your chocolates should be stored at room temperature in a container or area where there is airflow and a constant temperature (this will help eliminate a cloudy or whitish appearance on the chocolate).